1. Field of the Invention
The present invention relates to an active display device and a driving method for a pixel of an active display device. More particularly, the present invention relates to an active display device and a driving method for a pixel of an active display device having a decreased layout area and consumption current.
2. Description of the Related Art
Recently, active display devices such as active matrix organic lighting emitting diodes (“AMOLEDs”) are widely used for various electronic equipments. In the active display device, a pixel selected is driven to be illuminated for displaying an image data on a display panel. At this time, the illuminance is determined according to corresponding digital data.
Meanwhile, one of the conventional methods for driving the pixel is an ‘analog type driving method’. According to the analog type driving method, the selected pixel is illuminated with a constant illumination intensity during one unit frame period, as shown in FIG. 1. In the analog type driving method, the number of the intensity levels to be selectable corresponds to the bit number of the digital data. For example, if the bit number of the digital data is 4, then the number of the intensity levels is 16 (=24).
In the analog type driving method, the bit number to be converted is the same as the bit number of the digital data. For example, if the bit number of the digital data is 4, then 4 bits are required to be converted. Thus, 4 bit digital to analog conversion (“DAC”) is required for the analog type driving method.
In the analog type driving method, the bit number to be converted is increased as the bit number of the digital data is increased. Also, the layout area for DAC is increased as the number of the converted bits is increased. Furthermore, the consumption current for DAC is increased as the number of the converted bits is increased.